Project Summary/Abstract The human tendency to view the social world in terms of ?us? and ?them? emerges very early in ontogeny. By 6 months, infants orient more to people from the same racial or linguistic group as them (i.e., in-group) than those who are not (i.e., out-group). Infants also prefer in-group over out-group members as social partners and selectively learn from and imitate in-group individuals. However, why infants exhibit in-group preference is unclear. One possibility is that infants have a cognitive bias to attend to members of their own social group because in-group members are better sources of information than out-group members. Another possibility is that infants may simply feel more comfortable with familiar in-group individuals ? an affective response, rather than a higher order cognitive evaluation. Lower level processes may also contribute to in-group preferences as familiar in-group individuals trigger more mirroring of actions and intentions (i.e., mirror neuron system activity) than unfamiliar out-group individuals. On a behavioral level, these possibilities are extremely difficult to tease apart, but electroencephalography (EEG) can help distinguish such cognitive attentional, affective, and mirroring processes. Frontal EEG theta activity is associated with heightened attention that later predicts learning. Frontal EEG asymmetry in the alpha band is associated with fear responses toward strangers in infancy and the motivation to withdraw or approach. Event-related desynchronization (ERD) of the mu rhythm when observing another's actions is thought to reflect mirror neuron system activities. By investigating these EEG oscillatory activity in infants, the proposed project will evaluate the relative contributions of cognitive, affective, and mirroring processes on infants' preference for in-group individuals and how age and social environment affects such tendencies. EEG activity of infants from 8 months to 3 years of age will be recorded as they view adults who are racial in-group or out-group members. Infants are hypothesized to show less attention (i.e., less frontal theta activity), greater fear (i.e., greater right frontal asymmetry), and less mirroring (i.e., less mu ERD) toward out- group than in-group adults. With age, infants are expected to rely on more cognitive attentional processes than affective or mirroring processes when interacting with out-group members. EEG activities are expected to predict infants' subsequent behaviors (such as imitation, helping, and perspective-taking) toward in- and out-group members. This proposal will also explore the potential roles of social environment in shaping infants' neurocognitive responses to in- versus out-group individuals by examining the effects of family and neighborhood racial diversity on infant's neural and behavioral responses. This proposal will elucidate the underlying neurocognitive processes behind the early emerging tendency to prefer in- over out-group members and provide insight into reducing the beginnings of racial bias in infancy.